The Federal Court of Appeals has ruled that six of 12 legal challenges to the Trans Mountain pipeline expansion can go ahead.

Wednesday’s ruling will allow groups to appeal the second phase of the expansion, which the federal government approved for the second time in June.

Concerns raised about the pipeline include inadequate environmental protections and some First Nations’ beliefs that Ottawa had predetermined the outcome before entering into discussion.

The federal government bought the Trans Mountain pipeline for $4.5 billion in 2018.

The appeals court said the challenges would proceed on a “highly expedited schedule.”

The First Nations that were granted leave to appeal are the Upper Nicola Band; the Tsleil-Waututh Nation; the Squamish Nation; the Coldwater Indian Band; Chief Ron Ignace and Chief Rosanne Casimir, on their own behalf and on behalf of all other members of the Stk’emlupsemc Te Secwepemc of the Secwepemc Nation; and Aitchelitz, Skowkale, Shxwhá:y Village, Soowahlie, Squiala First Nation, Tzeachten, Yakweakwioose.

The court said the approved challenges are limited to the “narrow issue of the adequacy of the Government of Canada’s further consultation with Indigenous peoples and First Nations between August 30, 2018 and June 18, 2019 and related issues.”

The court said the decision to allow challenges based on First Nations consultations to proceed was made even after giving Ottawa “leeway” in its talks with the nations, as well as giving a high level of defence to the government’s right to approve the pipeline.

“Compliance with the duty to consult is not measured by a standard of perfection,” wrote Justice David Stratas in his reasons.

The appeals court first struck down Ottawa’s approval of the pipeline expansion in August, citing the National Energy Board’s failure to consider marine impacts and inadequate First Nations consultation.

The board re-approved the pipeline earlier this year, and the Trudeau government made the decision to proceed with the project on June 18.

In appeals that followed, First Nations said Canada again did not meaningfully consult with them.

Stratas wrote that the First Nations considered the further consultations rushed and as “window-dressing, box-ticking and nice-sounding words, not the hard work of taking on board their concerns, exploring possible solutions, and collaborating to get to a better place.”

He said the environmental challenges were denied because they were either the same as ones made in last August’s appeal, or ones that could and should have been made at that time. The court does not rehear old arguments.

Environmental concerns about the impact of increased marine traffic were dismissed because the National Energy Board’s “comprehensive, detail-laden, 678-page report” was found to have satisfied that requirement.

Environmental groups said they were disappointed with the decision.

“We remain committed to protecting the southern resident killer whales, fighting climate change, and holding Cabinet to account, and we will review our legal option in the coming weeks,” a statement from Ecojustice, Raincoast Conservation Foundation and Living Oceans Society said. “Given the urgency of this situation, we will not rule out taking our fight to the Supreme Court of Canada.”

The six parties granted leave to appeal must file notices of application for judicial review within seven days.